Therapy Analysis - Sickle cell anaemia
Can Sickle-Cell Anaemia Be Prevented?
Due to its genetic nature, children who inherit both the genes for sickle-cell anaemia will have the disease, but although this cannot currently be prevented, steps can be taken to reduce the risk.
Expectant parents who have a high risk for passing the disease down to their children have an opportunity to undergo a procedure called pre-implantation genetic diagnosis, which can improve the chance that two people with sickle cell trait will have a child with normal Hb. Eggs from the mother are fertilized with sperm from the father and are checked for sickle-cell anaemia. The mother's womb is then implanted with fertilized eggs not carrying the sickle-cell genes. However, this difficult procedure is not 100% effective nor widely available.
Research suggests that a cure is only possible through a
bone marrow transplant, but with the limitations
created by long waiting lists and transplant rejection, it
has led to a focus on embryonic stem cells, which can
be cultured to create any type of tissue. Dr Wai Kan, a
researcher at the University of California, genetically
engineered mice to carry the human genes with the
sickle-cell mutation. Embryonic stem cells at the earliest
stage of development (blastocysts) were then
extracted, and the defective Hb genes were replaced
with healthy types, giving rise to healthy blood cells.
The same method can be utilized with human
embryonic stem cells, in which the amended stem cells
from a cloned human embryo from a sufferer can be
injected back into the patient to produce a healthy
supply of RBCs. Still at an early stage, this technique
has many ethical, financial and production obstacles to
overcome, but it opens up a new alternative to nonstem
cell treatments, which are only efficacious in the
treatment of symptoms. Sangamo BioSciences, with the
help of a US NIH grant, has designed zinc-finger DNA
binding transcription factors that activate endogenousfoetal globin genes, rather than introducing foetal
globin genes, to compensate for the diseased adult ß-
globin gene. Other therapies following suit include
Cellerant Therapeutics' highly-purified haematopoietic
stem cell, CLT-001, and Cellectis' recombinant
meganucleases.
With the disease affecting a large proportion of the developing world, there is a necessity for organizations in the West to open up new avenues through funding, research and public awareness for the battle against sickle-cell anaemia.
Paul D'Souza
Image courtesy of NHLBI
